Reactive sintering and piezoelectric properties of 0.94Bi_0.5Na_0.5TiO₃–0.06BaTiO₃ ceramics with ZnO additive

抄録

Bismuth sodium titanate (Bi_0.5Na_0.5TiO₃, BNT) and its solid-solution with BaTiO₃ (BNT–BT) are promising lead-free piezoelectric ceramics. Around the morphotropic phase boundary (MPB), the 0.94BNT–0.06BT composition shows high piezoelectric performance. In this paper, we have investigated the effect of ZnO-doping on the reactive sintering and piezoelectric properties of 0.94BNT–0.06BT ceramics. Bi₂O₃, anhydrous Na₂CO₃, TiO₂ (anatase), BaCO₃ and ZnO powders were wet ball-milled in ethanol, cold isostatically pressed at 200 MPa for 10 min, and reactively sintered at 1150°C for 2 h in air. The relative density drastically increased from 83.3% (without ZnO) to 93.7% (with 0.5 mol% ZnO). The sample with 0.5 mol% ZnO showed the highest piezoelectric constant d₃₃ of 124 pC/N. Even by the one-step reactive sintering, the d₃₃ value was comparable with that of the two-step conventional sintering.